Ottawa outshot Calgary 22-6 and outscored them 3-1 in the deciding second period.
David Rittich made 32 saves in the loss, while Matt Murray turned aside 27 of the shots he faced.
Drake Batherson scored pair for the Sens, while Milan Lucic had the Calgary marker.
Rittich made a a fabulous save early in the first period as a streaking Batherson tipped a pass from Colin White right on target.
Then it was Austin Watson who was denied in the slot, Rittich slamming the pads together to deny his five-hole attempt.
The two teams were part of a NHL rarity on Feb. 25, playing a game with no penalties in Ottawa's 6-1 win.
During Calgary's 6-3 matinee victory Saturday, the ice to the box was worn down with 10 calls in the tilt, the Sens scoring all three of their tallies on six total chances.
The Flames had a man-up before the midway point of the opening frame but nothing doin'.
The ice slanted for the visitors after that, the Flames creating some great chances, Andrew Mangiapane feeding Mikael Backlund a one-timer that Murray stopped.
Then a dominant few shifts pinned the Sens in their zone, Murray first stopping a quick shot from Sean Monahan and then denying Elias Lindholm from point-blank range.
Josh Leivo then wired a shot off a rush that Murray also denied.
The Sens had a late powerplay in the first period, Tim Stützle having a lovely look on a cross-ice feed but unable to convert.
Artem Anisimov opened the scoring at 6:22 in the second period, taking a drop pass from Stützle and firing a shot that went in off the skate of Nikita Nesterov and changed direction to go farside.
Batherson then scored his first off a Calgary turnover just over two minutes later, leading to a Calgary timeout.
Lucic got the Flames on the board with a marker late in a Calgary powerplay at 10:20, firing a shot and then following his rebound for a second attempt that appeared to go off a Ottawa defender's skate and in.
